That kind of sentence is rarely written about a major presidential candidate. But I don't see a realistic third alternative (except for one long-shot, below).

Clinton is now hostage to the various investigations  the FBI, Congress, the courts  of her e-mails. The issue has already damaged her seriously by highlighting once again her congenital inability to speak truthfully. When the scandal broke in March, she said unequivocally that she "did not e-mail any classified material to anyone." That's now been shown to be unequivocally false. After all, the inspector general of the intelligence community referred her e-mails to the Justice Department precisely because they contain classified material.

The fallback  every Clinton defense has a fallback  is that she did not mishandle any material "marked" classified. But that's absurd. Who could even have been in a position to mark classified something she composed and sent on her own private e-mail system?

Moreover, what's prohibited is mishandling classified information , not just documents . For example, any information learned from confidential conversations with foreign leaders is automatically classified. Everyone in national security knows that. Reuters has already found 17 e-mails sent by Clinton containing such "born classified" information. And the State Department has already identified 188 e-mails on her server that contain classified information.

The truth-shaving never stops. Take a minor matter: her communications with Sidney Blumenthal. She originally insisted that these were just "unsolicited" e-mails from an old friend. Monday's document release showed that they were very much solicited ("Keep 'em coming when you can") and in large volume  306 e-mails, according to the New York Times' Peter Baker, more than with any other person, apparently, outside the State Department.

The parallel scandal looming over Clinton is possible corruption involving contributions to the Clinton Foundation while she was secretary of state. There are relatively few references to the foundation in the e-mails she has released. Remember, she erased 32,000 e-mails she deemed not "work-related." Clinton needs to be asked a straightforward question: "In sorting your private from public e-mails, were those related to the Clinton Foundation considered work-related or were they considered private and thus deleted?"

We are unlikely to get a straight answer from Clinton. In fact, we may never get the real answer. So Clinton marches on regardless. Who is to stop her?

Yes, Bernie Sanders has risen impressively. But it is inconceivable that he would be nominated. For one thing, he'd be the oldest president by far  on Inauguration Day older than Ronald Reagan, our oldest president, was at his second inaugural.

And there is the matter of Sanders being a self-proclaimed socialist in a country more allergic to socialism than any in the Western world. Which is why the party is turning its lonely eyes to joltin' Joe Biden.

Biden, who at 72 shares the Democrats' gerontocracy problem, is riding a wave of deserved sympathy. But that melts away quickly when a campaign starts. Even now, his support stands at only 18 percent in the latest Quinnipiac poll. For him to win, one has to assume that Sanders disappears and Biden automatically inherits Sanders' constituency.

That's a fantasy, modeled on 1968 when Bobby Kennedy picked up Eugene McCarthy's anti-Lyndon Johnson constituency. But Joe Biden is no Bobby Kennedy. And in a recent Iowa poll, Biden's support comes roughly equally from Clinton and Sanders. Rather than inheriting the anti-Clintonite constituency, he could instead be splitting it.

There is one long-shot possibility that might upend Clinton: Biden pledges to serve one term only and chooses Elizabeth Warren as his running mate  now. One-term pledges address the age problem but they are political poison, giving the impression of impermanence and mere transition. Warren cures that, offering the Democratic base  and the Sanders constituency  the vision of a 12-year liberal ascendancy.

When asked on Wednesday whether she had discussed such a ticket with Biden, Warren answered "it was a long conversation," a knowing wink in the form of a provocative nondenial.

I doubt a Biden-Warren ticket will happen, but it remains the only threat to Clinton outside of some Justice Department prosecutor showing the same zeal in going after Hillary Clinton as the administration did in going after David Petraeus.

Otherwise the Democrats remain lashed to Clinton. Their only hope is that the Republicans self-destruct in a blaze of intraparty warfare. Something for which they are showing an impressive talent.